WO2005014744A1

WO2005014744A1 - Coating composition and low dielectric porous siliceous material produced by using same

Info

Publication number: WO2005014744A1
Application number: PCT/JP2004/011136
Authority: WO
Inventors: Tomoko Aoki; Hiroyuki Aoki
Original assignee: Az Electronic Materials (Japan) K.K.
Priority date: 2003-08-12
Filing date: 2004-08-04
Publication date: 2005-02-17
Also published as: JP2006188547A; TW200507110A

Abstract

Disclosed is a coating composition which enables to produce a porous siliceous film which exhibits excellent mechanical strength, stably very low dielectric constant, and chemical resistance to various chemicals at the same time. Also disclosed is a method for producing a siliceous material using such a coating composition. The coating composition contains a polyalkyl silazane compound, a siloxy group-containing polymer and an organic solvent. Also disclosed are a siliceous material obtained by firing such a coating composition and a method for producing such a siliceous material.

Description

Specification

Coating composition and low dielectric porous siliceous material produced using the same

Technical field

[0001] The present invention relates to a coating composition. Further, the present invention relates to a method for producing a low dielectric siliceous material using the same, and a low dielectric siliceous film produced using the same. Further, the present invention relates to a semiconductor device comprising the low dielectric siliceous material thus manufactured. Background art

[0002] Electronic materials such as interlayer insulating films for semiconductors (IMD) are required to have lower dielectric constants as integrated circuits become faster and more integrated, and the relative dielectric constant of siliceous films is reduced. It is known to make the membrane porous in order to achieve this. Since the siliceous film generally has a hygroscopic property, the relative dielectric constant tends to increase with time depending on the surrounding environment.

[0003] As a method of preventing such a rise in relative dielectric constant with time, a method of making an organic siliceous film obtained by firing polyorganosilazane porous can be considered. Since the organic siliceous film thus obtained has a structure in which an organic group is bonded to the silicon atom of silica, the water repellency of the film itself is high and the relative permittivity due to moisture absorption over time is high. In addition to suppressing the rise, it is possible to obtain a porous film having heat resistance and environmental resistance required as an interlayer insulating film for semiconductors.

[0004] Further, higher integration of integrated circuits has also promoted the development of multilayer wiring process technology for more efficiently realizing miniaturization and multilayering of internal wiring in semiconductor devices. Such a technique involves, for example, embedding a wiring material such as Cu in the groove by a sputter reflow method or a CVD method, and removing the wiring material deposited outside the groove by a CMP (chemical mechanical polishing) method or the like. One that forms a wiring is given. With the progress of such trench wiring technology, the semiconductor device can be miniaturized in internal wiring, and can be further multilayered in combination with the surface flattening by the CMP method.

[0005] The high integration of such an integrated circuit requires an interlayer insulating film existing between wirings. In addition to lowering the dielectric constant of the material, it requires mechanical strength that can withstand the process of removing the wiring material by the CMP method.Furthermore, when removing the photoresist used in the wet stripping of the chemicals used in the CMP method, the When removing photoresist by chemicals and assing, it is also required to have chemical resistance to various chemicals such as chemicals for removing residues after assing.

Patent Document 1: JP 2002-75982A

Disclosure of the invention

Problems to be solved by the invention

[0006] Begurays and several methods have been studied to meet the above demands for siliceous materials. For example, the present inventors have found that a high-strength porous siliceous film can be obtained by firing a film of a composition containing a polyalkylsilazane and a polyacrylate or a polymethacrylate. (Patent Document 1). The porous siliceous film described in Patent Document 1 has an effect that a rise in relative dielectric constant over time due to moisture absorption can be suppressed. However, as a result of further studies by the present inventors, the porous silica film generally has an elastic modulus of 3 GPa or less when the relative dielectric constant is about 2.2, and the film strength is high. It turns out that there is room for improvement in terms of

[0007] On the other hand, when a multilayer wiring structure is formed using a porous film as an interlayer insulating film, the holes formed in the porous film may have smaller diameters, and may have uniform diameters. is important. If the porous insulating film is exposed to an etching gas, a stripping solution, or the like used when forming a multilayer wiring structure, the gas or the stripping solution may enter the large holes and erode. In addition, the stress and heat applied when forming metal wiring and other thin films on the porous film triggers the hole to expand, and furthermore, the local force of the hole becomes S leak purse, and the porous film becomes an insulating film. May not function as From such a viewpoint, it is known that the pore diameter of the pores of the porous membrane is desirably 2 nm or less. However, the conventional method usually produces only a porous film having fine pores having a pore size of 5 to 8 nm, and it is difficult to form a porous film having pores having a uniform pore size of 5 nm or less. Met.

Means for solving the problem

[0008] The present invention provides a polyalkylsilazane conjugate, a siloxy group-containing polymer, and an organic solvent. And a coating composition comprising:

[0009] Further, the siliceous material of the present invention is characterized in that the coating composition is formed by applying the coating composition on a substrate or filling a groove, followed by firing.

[0010] Further, a semiconductor device according to the present invention is characterized in that the above-mentioned siliceous material is included as an interlayer insulating film.

[0011] Further, in the method for producing a siliceous material according to the present invention, the above-mentioned coating composition is preliminarily calcined in a steam-containing atmosphere at a temperature of 50 to 300 ° C, and further calcined in a dry atmosphere at a temperature of 300 to 500 ° C. It is characterized by doing.

[0012] Further, the siliceous material according to the present invention is characterized in that it has 0.53 x m micropores inside.

The invention's effect

[0013] The present invention solves a problem in the production of a conventional porous material as described above, and provides an excellent mechanical strength that can withstand the latest high integration processes such as the damascene method. Easily produce porous siliceous materials with small pores, exhibiting a very low dielectric constant, especially less than 2.5, exhibiting a stable dielectric constant and having chemical resistance to various chemicals. To provide a coating composition that can be used.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Polyalkylsilazane compound

The polyalkylsilazane conjugate in the present invention has an alkyl-substituted silazane bond. Although the structure is not limited, preferred polyalkylsilazane compounds are preferably those having a repeating unit represented by the following general formula (1) and a unit represented by the general formula (2) or (3). Any of them is included.

[Chemical 1]

In the above formulas (1) and (3), R ^{1 to} R ¹¹ each represent a hydrogen atom or an alkyl group having 13 to 13 carbon atoms.

R ⁵ and R ⁶ , and R ⁹ —R ¹¹ are not all hydrogen. In a more preferred embodiment, R ¹ —R ¹¹ in each formula are as follows.

In the above formula (1), R ¹ represents a hydrogen atom or an alkyl group having 13 to 13 carbon atoms, but it is not easy for all R ¹ of the entire compound to be hydrogen at the same time.

R ² — R ⁴ are each independently a hydrogen atom or a C 1-3 alkyl group R ² —

It is difficult for all of R ⁴ to be hydrogen at the same time

p, q, and r are each 0 or 1, and 0≤p + q + r≤3.

Here, in the general formula (1), when R ¹ is a methyl group and R ² —R ⁴ are present, it is preferable that all of them are hydrogen.

In the above formula (2), R ^{5 and} R ⁷ are each independently a force S representing a hydrogen atom or an alkyl group having 13 carbon atoms, and all R ⁵ and R ⁶ of the whole compound are simultaneously hydrogen. Never.

Here, in the general formula (2), it is preferable that one of R ⁵ and R ⁶ is a hydrogen atom, the rest is a methyl group, and R ⁷ is a hydrogen atom.

In the above formula (3), R ⁸ R ¹¹ is a force S independently representing a hydrogen atom or an alkyl group having 13 carbon atoms, and all R ⁹ R ¹¹ of the whole compound are simultaneously hydrogen. There is no.

[0021] In the general formula (3), a R ⁸ is a hydrogen atom, R ⁹ - that all of R ¹¹ is a methyl group Is preferred.

In the present invention, a polyalkylsilazane compound compound containing a repeating unit represented by the general formula (1) and at least one of the repeating units represented by the general formula (2) or (3) It is particularly useful in that it can prevent gelling during storage of the tinting composition. In this case, it is preferable that the number of the repeating units represented by the general formula (1) is 50 mol% or more of the total number of the units represented by the general formulas (1) to (3). More preferably, it is particularly preferably at least 90 mol%. When the repeating unit force of the general formula (1) is at least 50 mol% with respect to the total number of the repeating units of the general formula (1)-(3), problems such as uneven repelling and coating unevenness are less likely to occur during film formation. It is.

[0023] The polysilazane compound according to the present invention preferably has a number average molecular weight of 100 or more in order to improve the coating properties of the coating composition, particularly the coating properties when applying by a spin coating method. In addition, the polysilazane conjugate according to the present invention preferably has a number average molecular weight of 50,000 or less in order to suppress the gelation of the composition by appropriately setting the number of crosslinking groups. In the present invention, a particularly preferred polyalkylsilazane conjugate comprises a repeating unit of the general formula (1) and at least one unit of the general formula (2) or (3). . In the present invention, the number average molecular weight of the polyalkylsilazane conjugate is preferably from 100 to 50,000, more preferably from 1,000 to 20,000.

[0024] These polyalkylsilazane conjugates can be used in the case of a polyalkylsilazane containing a repeating unit of the general formula (1) in an ammonolysis process for synthesizing a normal polysilazane, which is obvious to those skilled in the art. (R iCl) is represented by the repeating unit of the general formula (2).

Three

Polyalkylsilazane containing dialkyldichlorosilane (R ⁵ R ⁶ SiCl)

2 Starting with trialkylchlorosilane (R ⁹ R ¹⁰ R SiCl) for polyalkylsilazane containing units of general formula (3) and starting from a mixture of these for polyalkylsilazane containing both of these repeating units It is obtained by using it as a raw material. The mixing ratio of these chlorosilanes determines the abundance ratio of each unit.

[0025] Siloxy-containing polymer

The coating compositions according to the invention comprises a siloxy group-containing polymer _c The union contains a siloxy group (one Si—o —)-containing monomer as a polymerized unit, and has a main chain

, A side chain, or a terminal unit contains a siloxy group.

Examples of the group containing a siloxy group include a trimethylsiloxy group, a dimethylbutylsiloxy group, a methylhydrosiloxy group, a dimethylsiloxy group, a phenylmethylsiloxy group, a diphenylsiloxy group, a methylvinylsiloxy group, and a phenyl group. 2-vinylsiloxy, 2- (trimethoxysilyl) ethyl (meth) acryl, γ- (trimethoxysilyl) propyl (meth) acryl, 2- (trimethylsiloxy) ethyl (meth) acryl, γ — (Trimethylsiloxy) propyl (meth) acrylic group, trimethylsiloxymethacrylic group, trimethylsilyloxysiloxanyl group and the like. Here, the (meth) acryl group refers to either an acryl group or a methacryl group.

If the siloxy group-containing polymer according to the present invention contains the above-mentioned siloxy group, it may or may not contain a polymer unit containing no siloxy group. Examples of such a siloxy group-free polymerized unit include methyl (meth) acrylic acid, isobutyl (meth) acrylic acid, η-butyl (meth) acrylic acid, tert-butyl (meth) acrylic acid, polyethylene glycol Forces such as side, polypropylene oxide, polypropylene glycol (meth) acrylic acid and the like are not limited to these. Of these, the siloxy group-containing polymer is preferably a polymer containing a polymer unit selected from the group consisting of acrylic acid, methacrylic acid, and a polyethylene oxide compound.

[0028] An example of this polyethylene oxide compound is shown below as a general formula.

HO- (CH CH O) -L- (SiR '100%) _SiR' (A)

2 2 m 2 n 3

Here, R ′ is an arbitrary substituent such as hydrogen, an alkyl group, an alkoxy group and the like, and R ′ in one molecule may be a mixture of a plurality of types. R ′ is a polymerizable group, and can be polymerized with another monomer unit.

L is a linking group, for example, a single bond, an alkylene group, or the like.

m and n are numbers representing the degree of polymerization.

[0029] The molecular weight of the siloxy group-containing polymer can be arbitrarily selected as long as the effect of the present invention is not impaired. Or steam It is preferable that the molecular weight of the polymer is not less than a certain value so as to form a porous film by being emitted, but is not more than a certain value from the viewpoint of preventing the generation of voids and a decrease in film strength due to the void. Is preferred. These lower and upper limits are appropriately selected depending on the type of the siloxy group-containing polymer used. When the siloxy group-containing polymer used in the present invention contains a polyethylene oxide compound as a polymerized unit, its molecular weight is preferably 100 5,000, more preferably 500 2,000. . Further, when the siloxy group-containing polymer contains acrylic acid or methacrylic acid as a polymerized unit, the molecular weight thereof is preferably 1,000, 80,000, and the molecular weight is preferably 10,000, 20,000 to 20,000. Reason better than mosquito.

[0030] More preferred siloxy group-containing polymers are polymers containing 2- (trimethylsiloxy) ethyl methacrylic acid in the polymerized units and polymers containing hydroxy (polyethyleneoxy) propyl / polydimethylsilicone in the polymerized units. . Among these, preferred specific examples of the siloxy group-containing polyethylene oxide compound include α- [3- [1,1,3,3-tetramethyl-11-[(trimethylsilyl) oxy] disiloxanyl] propynole] —ω-hydroxy-poly (oxy) 2,3-ethanexyl), hydroxy (polyethyleneoxy) propyl polydimethyl silicone, and MCR-C13 manufactured by Gelest (Pennsylvania, USA).

[0031] In such a siloxy group-containing polyethylene oxide compound, the structure of the polyethylene oxide is not particularly limited, but from the viewpoint of appropriately maintaining the viscosity, the weight of the ethyleneoxy moiety is 30 to 90% relative to the weight of the molecule. The weight of the siloxy group in the polysiloxy structure is preferably 10 to 40%.

[0032] In the siloxy group-containing polyethylene oxide compound or a copolymer containing the same as a monomer unit, the hydroxyl group-terminated polyethylene oxide structure crosslinks with the above-mentioned polyalkylsilazane compound. It is thought to increase the pore size and make the pores more porous. Furthermore, the siloxy group-containing polyethylene oxide has an effect that, when sublimated by heating, a part of the siloxy group remains in the fired film of polyalkylsilazane as a matrix, thereby producing a silica material having higher strength. Play.

[0033] It is essential that the siloxy group-containing polymer in the present invention contains a siloxy group. White The proportion of the polymerized unit containing a xy group is preferably 1% or more, more preferably 10% or more, more preferably 30%, based on the total number of polymerized units constituting the siloxy group-containing polymer. It is especially preferred that it is more than.

[0034] ^ mm

The coating composition according to the present invention is obtained by dissolving or dispersing the above-mentioned polyalkylsilazane conjugate and acetylethoxysilane conjugate, and, if necessary, other additives described later in an organic solvent. At this time, it is preferable to use an inert organic solvent having no active hydrogen as the organic solvent. Such organic solvents include aromatic hydrocarbon solvents such as benzene, tolylene, xylene, ethylbenzene, getylbenzene, trimethylbenzene, and triethylbenzene; cyclohexane, cyclohexene, decahydronaphthalene, ethylcyclohexane, and methylcyclohexane. Alicyclic hydrocarbon solvents such as hexane, p-menthine, dipentene (limonene); ether solvents such as dipropyl ether and dibutyl ether; ketone solvents such as methyl isobutyl ketone; propylene glycol monomethyl ether acetate And the like.

[0035] Other additives

The coating composition according to the present invention can also contain other additive components as required. Examples of such a component include a siloxy group-free polymer.

The siloxy group-free polymer that can be used in the coating composition according to the present invention includes a homopolymer and a copolymer of a (meth) acrylic acid ester that can use any polymer. Those selected from the group and containing a carboxyl group or a hydroxyl group in a part of the side groups are preferable. Such a polymer has the effect of making the pores of the formed siliceous material small and uniform. Examples of such a polymer include a homopolymer of an acrylate ester such as polymethyl acrylate and polyethyl acrylate; and a homopolymer of a methacrylate ester such as polymethyl methacrylate and polyethyl methacrylate; Ester copolymers, such as poly (methyl acrylate-co-ethyl acrylate); methacrylate copolymers, such as poly (methyl methacrylate-co-ethyl methacrylate); acrylate esters and methacrylate esters And copolymers such as poly (methyl acrylate) -Ethyl methacrylate). When the polymer is a copolymer, a random copolymer, a block copolymer or any other sequence having no restriction on the monomer sequence can be used.

[0037] The monomers constituting the homopolymer and copolymer of the (meth) acrylate include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, Forces include, but are not limited to, methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, and the like. In particular, methyl methacrylate and n-butyl methacrylate and n-butyl acrylate and i-butyl acrylate are more preferred from the viewpoint of compatibility with polyalkylsilazane.

[0038] The carboxyl group and the hydroxyl group contained in such a (meth) acrylic acid ester polymer form a cross-link with the polyalkylsilazane conjugate. Since the cross-linking reaction affects the final strength and structure of the siliceous material, the amount of carboxyl groups and hydroxyl groups is important. In order to obtain a sufficient crosslinked structure, the amount of the carboxyl group and the hydroxyl group is preferably at least 0.01 mol%, more preferably at least 0.1 mol%, based on the total number of monomers constituting the polymer component. Is more preferred. Further, in order to prevent gelling by excessive crosslinking, the content is preferably 50 mol% or less, more preferably 30 mol% or less.

When a polymer containing no siloxy group is used, the polymer has a molecular weight of 1,000 or more so that the polymer sublimates, decomposes, or evaporates at an appropriate temperature to form a porous film. More preferably, it is more preferably 10,000 or more. On the other hand, the molecular weight of the polymer is preferably 800,000 or less, more preferably 200,000 or less, from the viewpoint of preventing voids and the resulting decrease in film strength.

[0040] The coating composition according to the present invention can also contain other additive components as necessary. Examples of such a component include a viscosity modifier, a crosslinking accelerator, and the like. In addition, a phosphorus compound, for example, tris (trimethylsilyl) phosphate can be contained for the purpose of gettering effect of sodium when used in a semiconductor device. Furthermore, in order to promote the reaction of the polymer component in the coating composition, a reaction accelerator, for example, an acetooxysilane compound, may be added. Acetoxysilane compound The material sometimes exerts an action to make the fine pores formed in the calcined siliceous material small and uniform.

[0041] Coating composition

The polymerizable composition according to the present invention is obtained by dissolving or dispersing the polyalkylsilazane compound, the siloxy group-containing polymer, and other additives as necessary in the organic solvent, and reacting the components. To form a coating composition. Here, the order of dissolving each component in the organic solvent is not particularly limited, and two or more solutions, for example, a solution of the polyalkylsilazane conjugate and a solution of the siloxy group-containing polymer are mixed. You can.

[0042] After mixing the components, if necessary, the mixture is physically stirred while heating, whereby a homogeneous coating composition having a cross-linked bond can be obtained. When heating, it is generally heated at 3080 ° C, but this temperature varies depending on the type of components used. Care must be taken especially when the temperature is excessively high because the composition may gel. The stirring time depends on the type and temperature of the components to be reacted, but is generally about 124 hours. Further, it is preferable to perform ultrasonic dispersion treatment in a hot water bath at 30-80 ° C for about 5 to 90 minutes, because it accelerates the reaction.

[0043] Further, the solvent can be replaced after the components are reacted.

[0044] The amount of the siloxy group-containing polymer according to the present invention, when used, is preferably based on the weight of the polyalkylsilazane compound in order to effectively realize a porous silica material. Is used in an amount of 5% by weight or more, more preferably 10% by weight or more, particularly preferably 20% by weight or more. On the other hand, in order to prevent a decrease in film strength due to generation of voids or cracks, it is preferable to use the polyalkylsilazane conjugate in an amount of preferably not more than 50% by weight.

The content of each of the above components varies depending on the intended use of the coating composition. However, the solid content is not less than 5% by weight in order to form a siliceous material having a sufficient thickness. In order to secure the storage stability of the coating composition and to maintain the viscosity appropriately, it is preferably 50% by weight or less. That is, it is generally preferable that the solid content is 5 to 50% by weight based on the whole coating composition. Is more preferable. Usually, by setting the solid content to 10 to 30% by weight, a generally preferable film thickness, for example, 2000 to 8000 A, can be obtained.

[0046] Method for producing silica material

The coating composition according to the present invention is applied onto a substrate or filled in a mold or groove, and then dried as necessary to remove excess organic solvent, and then calcined to obtain a siliceous material. be able to. When the siliceous material according to the present invention is applied to an electronic component such as a semiconductor device, usually, the coating composition applied on the substrate is baked into a siliceous material, so that the silica material is directly formed on the semiconductor device. It is common to form porous materials

[0047] Examples of a method of applying the coating composition to the substrate surface include a conventionally known method, for example, a spin coating method, a dip method, a spray method, a transfer method, and the like.

[0048] The coating film formed on the substrate surface is preliminarily fired in a steam atmosphere after removing (drying) an excess organic solvent as necessary. Here, the term “steam atmosphere” refers to an atmosphere in which the relative humidity at 23 ° C is 40% or more. At this time, gases other than water vapor forming the atmosphere are air, nitrogen, helium, argon, and the like. Precalcination is performed at a temperature of 50-350 ° C, preferably 100-300 ° C. This preliminary firing can be performed stepwise or continuously while increasing the temperature.

[0049] After this pre-baking, if necessary, after leaving for a short time (for example, 3 to 30 minutes) in a humidified atmosphere, or for a long time (for example, 24 hours) in an air atmosphere, Heat and bake. This firing step is performed in a dry atmosphere. Here, the dry atmosphere is an atmosphere containing almost no water vapor such as dry air, dry nitrogen, and dry helium, and an atmosphere having a relative humidity at 25 ° C of 10% or less.

[0050] The calcination temperature is 300 to 500 ° C, preferably 350 to 450 ° C, and the calcination and firing time varies depending on the calcination temperature and the components, but is generally 1 minute to 1 hour. From the viewpoint of productivity, the firing temperature is preferably 300 ° C or higher to complete the firing step in as short a time as possible, but 500 ° C or lower to maintain the quality of the formed siliceous material. It is preferable that

[0051] By the above calcination step, SiH, SiR (R: hydrocarbon group) and Of the SiN bonds, only the SiN bonds are oxidized and converted into SiO bonds, forming a siliceous material having unoxidized SiH and SiR bonds. As described above, in the formed siliceous material, the SiO bond formed by selectively oxidizing the SiN bond and the unoxidized SiH and SiR bonds can be present. Thus, a siliceous material of In general, the dielectric constant of a siliceous material decreases as the density of the siliceous material decreases, while the decrease in the density of the siliceous material causes the adsorption of water, which is a high dielectric substance. Therefore, if the siliceous material is left in the air, the dielectric constant of the film may increase, which may cause a problem. On the other hand, in the case of the siliceous material according to the present invention containing SiH or SiR bonds, since these bonds have water repellency, it is possible to prevent the adsorption of water at a low density even at a low density. Therefore, the siliceous material according to the present invention has a great advantage that the dielectric constant of the siliceous material hardly increases even when it is exposed to an atmosphere containing water vapor. Further, since the siliceous material according to the present invention has a low density, there is an advantage that the internal stress of the film is small and cracks are hardly generated.

[0052] In the firing of the coating composition according to the present invention, fine pores having a pore diameter of 0.5 to 3 nm are mainly formed inside the siliceous material. And this siliceous material has substantially no micropores with a pore diameter exceeding 5 nm. The diameter of these micropores can be measured by the X-ray diffuse scattering method. As an apparatus that can be used for this measurement, ATX-G type multifunctional X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.) S is used. It is considered that these fine pores are formed by the decomposition of the acetoxysilane bonded product and the decomposition product being evaporated or sublimated. Due to the presence of the micropores, the density of the siliceous material further decreases, and as a result, the relative dielectric constant of the siliceous material further decreases.

[0053] The porous siliceous material according to the present invention has excellent mechanical strength because extremely fine pores can be formed. Specifically, the porous siliceous material according to the present invention exhibits remarkably high mechanical strength as a porous material having an elastic modulus of 3 GPa or more, and in some cases, 5 GPa or more by a nanoindentation method described later. .

[0054] Accordingly, in order to have both mechanical strength and various chemical resistances that can withstand the wiring material removal process by the CMP method, it is used as an interlayer insulating film compatible with the latest high integration processes such as the damascene method. It is possible. Further, since the water-repellent groups derived from the polyalkylsilazane compound which is a matrix component of the siliceous material according to the present invention sufficiently remain after calcination, the siliceous material can be left in an atmosphere containing water vapor even if it is left in an atmosphere containing water vapor. The rate hardly rises. As described above, according to the present invention, the lowering of the density of the siliceous material (SiH, SiR) due to the binding components (SiH, SiR) and the lowering of the density of the entire film due to the micropores are combined with less than 2.5, A porous siliceous material that can stably maintain an extremely low relative dielectric constant of 2.0 or less, or about 1.6 in some cases, can be obtained.

According to another property of the porous siliceous material according to the present invention, its density is 0.5 to 1.6 g / cm ³ , preferably 0.8 to 1.4 gZcm ³ , and its crack limit film thickness is 1. Ozm or more, preferably 5 xm or more, and its internal stress is 80 MPa or less, preferably 50 MPa or less. Further, the Si-containing group present as SiH or SiR (R: hydrocarbon group) bond contained in the siliceous material is 10 to 100 atomic%, preferably 10 to 100 atomic%, based on the number of S ^ g elements contained in the material. Is 25 75 atomic%. The content of Si present as SiN bonds is 5 atomic% or less. The thickness of the porous siliceous material obtained after the calcination varies depending on the use of the surface of the substrate, and is usually 0.01-1 μ μη, preferably 0.1-2 μΐη. In particular, when it is used as an interlayer insulating film of a semiconductor device, the thickness is preferably 0.1-2 / m.

[0057] The porous siliceous material according to the present invention has a low density as described above, and has a crack limit film thickness, that is, a maximum film thickness that can be formed without causing film cracking. It also has the advantage of showing a high value of μΐη or more. In the case of a conventional siliceous material, its crack limit film thickness is about 0.5-1.5 / im.

As described above, the siliceous material according to the present invention has a low dielectric constant, a low density, a high water repellency, a high chemical resistance, and a high mechanical strength as compared with the conventional siliceous material. In addition, it can maintain a low dielectric constant stably, and is particularly preferable when applied to an interlayer insulating film in a semiconductor device.

[0059] The present invention is described below using examples. The evaluation of the physical properties of the siliceous material is summarized at the end.

Reference example 1

(Synthesis of Polymethylsilazane (1))

A stainless steel tank with a capacity of 5 liters is equipped with a stainless steel tank for supplying raw materials. I wore it. After the inside of the reactor was replaced with dry nitrogen, 780 g of methyltrichlorosilane was put into the stainless steel for raw material supply, and this was pressure-fed into the reaction tank with nitrogen and introduced. Next, a raw material supply tank containing pyridine was connected to the reactor, and 4 kg of pyridine was similarly pumped and introduced with nitrogen. The pressure of the reactor was adjusted to 1.0 kg / cm ² , and the temperature of the mixture in the reactor was adjusted to 14 ° C. Ammonia was blown into the reactor with stirring, and when the pressure in the reactor reached 2.0 kg / cm ² , the supply of ammonia was stopped. The reactor pressure was lowered by opening an exhaust line, and then dry nitrogen was blown into the liquid phase for 1 hour to remove excess ammonia. The obtained product was subjected to pressure filtration under a dry nitrogen atmosphere using a pressure filter to obtain 3200 ml of a filtrate. When pyridine was distilled off using an evaporator, about 340 g of polymethylsilazane was obtained.

[0061] The number average molecular weight of the obtained polymethylsilazane was measured by gas chromatography using a chloroform-form developing solution, and was 1800 in terms of polystyrene. Infrared absorption scan vectors (hereinafter, referred to as IR spectrum) was measured, 3350Cm- ¹ and 1200cm- ¹ NH bonded to based absorption around, 2900Cm- ¹ and 1250Cm- ¹ of Si- C bond to based absorbent, and 1020 Absorption due to Si—N-Si bond of —820 cm— ¹ was observed.

Reference example 2

(Synthesis of Polymethylsilazane (2))

Synthesis was performed in the same manner as in Reference Example 1 except that a mixture of 720 g of methyltrichlorosilane and 656 of dimethyldichlorosilane was used instead of 780 g of methyltrichlorosilane as a raw material.

Og of polymethylsilazane was obtained.

[0063] The number average molecular weight of the obtained polymethylsilazane was measured by gas chromatography using a chloroform solution as a developing solution, and was found to be 1400 in terms of polystyrene. Infrared absorption spectra were measured to show absorption at 3350 cm- ¹ and 1200 cm- ^{1 due} to N--H bonds, absorption at 2900 cm- ¹ and 1250 cm- ^{1 due} to SC bonds, and 1020 820 cm- ¹ — Absorption due to N—Si bond was observed.

Example 1

[0064] 15% propylene glycol monomethyl ether acetate polymethyl silazane synthesized in Reference Example 1 (hereinafter, PGMEA and Re, U) to the solution 80 g, isobutyl methacrylate 70 mole ^_0/0 A solution obtained by dissolving 3 g of a copolymer (molecular weight: about 100,000) of 2- (trimethylsiloxy) ethyl methacrylic acid in 30 mol% in 17 g of PGMEA was mixed and thoroughly stirred. Subsequently, the solution was filtered with a PTFE syringe filter (manufactured by Advantech) having a filtration accuracy of 0.2 micron. The filtrate was applied on a silicon wafer having a diameter of 10.2 cm (4 inches) and a thickness of 0.5 mm using a spin coater at 3000 rpm for 20 seconds, and further dried at room temperature for 5 minutes. The silicon wafer was heated at 150 ° C for 3 minutes in an air atmosphere (relative humidity 40% at 23 ° C), and then for 3 minutes on a 250 ° C hot plate. This film was allowed to stand in an air atmosphere (23 ° C, 40% relative humidity) for 24 hours, and then calcined in a dry nitrogen atmosphere at 400 ° C for 30 minutes to obtain a siliceous film.

[0065] The IR spectrum of the obtained siliceous film is

And Si_〇 based on the binding absorption ASOcnT ^{^1,} 1270cm- ¹ and 780Cm- ¹ of Si_C based binding absorption, absorption was observed based on the C-H bond 2970cm- ^{^1,} 3350cm- ¹ and 1200Cm- ¹ of N The absorption based on the —H bond and the absorption based on the copolymer of isobutyl methacrylate and 30- (trimethylsiloxy) ethyl methacrylate were lost.

When the obtained siliceous film was evaluated, the relative dielectric constant was 2.20, the density was 1. lg / cm ³ , the internal stress was 36 MPa, and the crack limit film thickness was 5 / m or more. After leaving the obtained film in the air at a temperature of 23 ° C and a relative humidity of 50% for one week, the relative dielectric constant was measured again, and there was no change at all.

[0067] The modulus of elasticity of this film by a nanoindentation method was 4.5 GPa.

ACT-970 (manufactured by Ashland Chemical Company, Ohio, USA), ST-210 and ST250 (manufactured by ATMI, Inc., Connecticut, USA), EKC265 and EKC640 (manufactured by Ashland Chemical Company, Ohio) Using EKC Technology, Inc. (California, USA), the resistance (compatibility) test of the siliceous film was performed, and the etching rate was 0.5 A / min or less, respectively. Was also less than 1.0%.

Further, when the pore size of the siliceous film was measured by the X-ray diffuse scattering method, the average pore size was 2 nm.

Example 2 [0070] to 20% PGMEA solution 160g of polymethyl silazane synthesized in Reference Example 2, a copolymer of Echirenki side 50 mole ^_0/0 and dimethylsiloxane 50 mole ^_0/0 (molecular weight: about 1,000) and 8g The solution dissolved in 32 g of PGMEA was mixed and thoroughly stirred. Subsequently, the solution was filtered through a PTFE syringe filter (manufactured by Advantech) having a filtration accuracy of 0.2 micron. The filtrate was applied on a silicon wafer having a diameter of 20.3 cm (8 inches) and a thickness of lmm using a spin coater at 3500 rpm / 20 seconds, and further dried at room temperature for 5 minutes. The silicon wafer was heated at 150 ° C for 3 minutes in an air atmosphere (relative humidity 40% at 23 ° C), and then for 3 minutes on a 250 ° C hot plate. This film was left in a humidifier at 70 ° C and a relative humidity of 85% for 3 minutes, and calcined in a dry nitrogen atmosphere at 400 ° C for 10 minutes to obtain a siliceous film.

[0071] The obtained IR spectrum of the silica membrane, 1020Cm- and 440Cm- ¹ of Si_〇 based binding absorption, 1290cm- ¹ and 770Cm- ¹ of Si_C based binding absorption, 2980cm- ¹ of the CH bond absorption was observed based, absorption that is based on 3350Cm- ¹ and 1200Cm- ¹ of NH bonds, and absorption based on a copolymer of ethylene key side and dimethylsiloxane disappeared.

When the obtained siliceous film was evaluated, the relative dielectric constant was 2.24, the density was 1.2 g / cm ³ , the internal stress was 35 MPa, and the critical crack thickness was 5 / m or more. After leaving the obtained film in the air at a temperature of 23 ° C and a relative humidity of 50% for one week, the relative dielectric constant was measured again, and there was no change at all.

[0073] The modulus of elasticity of this film by the nanoindentation method was 5. OGPa.

[0074] A resistance test of a siliceous film was performed using an etching residue stripping solution ACT-970 (manufactured by Ashland Chemical), ST-210 and ST250 (manufactured by ATMI), EKC265 and EKC640 (manufactured by EKC). And the etching rate was 0.8 A / min or less, respectively, and the increase in the dielectric constant by the test was 1.1% or less.

[0075] where further a pore size siliceous film was measured by X-ray diffuse scattering method, the average pore diameter was 1. 7n m ₀

Comparative Example 1

[0076] Poly n was added to 80 g of a 15% solution of polymethylsilazane in dibutyl ether synthesized in Reference Example 1. —A solution of 3 g of butyl methacrylate (molecular weight: about 160,000) dissolved in 17 g of dibutyl ether was mixed and thoroughly stirred. Subsequently, the solution was filtered with a PTFE syringe filter (manufactured by Advantech) having a filtration accuracy of 0.2 micron. The filtrate was applied to a silicon wafer having a diameter of 10.2 cm (4 inches) and a thickness of 0.5 mm using a spin coater under the conditions of 2000 rpm / 20 seconds, and further dried at room temperature for 5 minutes. The silicon wafer was heated in an air atmosphere (relative humidity at 23 ° C: 40%) at 150 ° C for 3 minutes, and then on a hot plate at 250 ° C for 3 minutes. This film was allowed to stand in an air atmosphere (23 ° C., 40% relative humidity) for 24 hours, and then calcined in a dry nitrogen atmosphere at 400 ° C. for 30 minutes to obtain a siliceous film.

[0077] The IR spectrum of the obtained siliceous film is

And ASOcnT ¹ absorption based on Si_〇 bond, 1270 cm— ¹ and 780 cm— ¹ absorption based on Si_C bond, 2970 cm ¹ absorption based on C—H bond, 3350 cm— ¹ and 1200 cm— ¹ N— Absorption based on H-bonds and absorption based on poly n-butyl methacrylate were burned out.

When the obtained siliceous film was evaluated, the relative dielectric constant was 2.31, the density was 1. lg / cm ³ , and the internal stress was 35 MPa.

[0079] The elastic modulus of this film by the nanoindentation method was 2.6 GPa, which was lower than that of the siliceous film according to the present invention.

Further, when the pore size of the siliceous film was measured by the X-ray diffuse scattering method, the average pore size was 7 nm, which was larger than the siliceous film according to the present invention.

[Evaluation Method of Physical Properties of Siliceous Film] Pyrex (registered trademark: manufactured by Dow K. Jung Co., Michigan, USA) glass plate (thickness: lmm, size: 50 mm × 50 mm) was diluted with a neutral detergent and diluted. Na〇H aqueous solution, diluted HHO aqueous solution

twenty four

Thoroughly wash and dry. An aluminum film is formed on the entire surface of this glass plate by a vacuum evaporation method (thickness: 0.2 zm). _{0 A} sample composition solution is applied on this glass plate by a spin coating method to form a film. To remove, rub the four corners of the glass plate with a cotton swab to remove the film (3 mm x 3 mm). Subsequently, it is converted into a siliceous film according to the method of each example. The obtained siliceous film is covered with a stainless steel mask, and an aluminum film is formed by vacuum evaporation. 18 patterns of 2mm x 2mm square and 2zm thick . The capacitance is measured at 100 kHz using a 4192ALF impedance analyzer (Yokogawa 'Hyu I Packard). The film thickness is measured using an M-44 spectroscopic ellipsometer (A. Woolam, Nebraska, USA). The relative permittivity is the average of the values calculated by the following formula for all 18 patterns.

(Relative permittivity) = (Capacitance [pF]) X (Film thickness [z m]) Z35.4

[0082] Any degree

A silicon wafer with a diameter of 10.16 cm (4 inches) and a thickness of 0.5 mm is weighed with an electronic balance. The sample composition solution is applied by spin coating to form a film, converted into a siliceous film according to the method of each example, and the weight of the silicon wafer with the film is measured again with an electronic balance. The film weight is the difference between the weight of the wafer before and after the film formation. The film thickness is measured with an M-44 spectroscopic ellipsometer (JA Woolam). The film density is calculated according to the following equation. (Film density [g / cm ³ ]) = (Film weight [g]) / (Film thickness [/ im]) /0.008

[0083] Internal stress

The sled of a silicon wafer of 20 · 32 cm (8 inches) in diameter and lmm thickness is input to a FLX-2320 laser-internal stress measuring instrument (KLA—Tencor, California, USA). Further, a sample composition solution is applied to this silicon wafer by spin coating to form a film, converted into a siliceous film according to the method of each example, and returned to room temperature (23 ° C.). Measure the internal stress with an internal stress meter. The film thickness is measured with an M-44 type spectroscopic ellipsometer (manufactured by J.A. Woolam).

[0084] crack ^

A sample composition solution is applied to a silicon wafer having a diameter of 10.16 cm (4 inches) and a thickness of 0.5 mm by a spin coating method to form a film, which is converted into a siliceous film according to the method of each example. Adjust the solid concentration of the sample composition solution or the number of revolutions of the spin coater at the time of coating to prepare a sample whose film thickness is changed in the range of about 0.5 zm to about 5 zm. The surface of the film after calcination is observed under a microscope (120x), and the presence or absence of cracks in each sample is examined. The maximum film thickness without cracks is defined as the crack limit film thickness.

[0085] Modulus of elasticity (nanoindentation method) A sample composition solution is applied to a silicon wafer having a diameter of 20.32 cm (8 inches) and a thickness of lmm by spin coating to form a film, which is converted into a siliceous film according to the method of each example. Using the resulting siliceous film, the elastic modulus is measured using a mechanical property evaluation system for thin films (Nano Indenter DCM manufactured by MTS Systems, USA).

[0086] Etching rate

It is calculated by treating the siliceous film using the etching residue stripping solution described in each example, and dividing the amount of change in film thickness before and after the treatment by the treatment time. The film thickness is measured using a M-44 type spectroscopic ellipsometer (manufactured by J.A. Woolam).

[0087] Pore measurement

A sample composition solution is applied to a silicon wafer having a diameter of 20.32 cm (8 inches) and a thickness of lmm by spin coating to form a film, which is converted into a siliceous film according to the method of each example. The pore size of the obtained siliceous film is measured by an X-ray diffuse scattering method using a multifunctional X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.) for evaluating the surface structure of ATX-G.

Industrial applicability

The present invention is to provide a porous siliceous film having a well-balanced combination of stable low dielectric constant, mechanical strength capable of withstanding the latest fine wiring process, and various chemical resistances. By using the porous siliceous film according to the present invention as an interlayer insulating film of a semiconductor device, it is possible to further increase the degree of integration and multilayering of an integrated circuit.

As described above, the present invention is applied to a force that is most preferably applied to form an interlayer insulating film in an electronic material such as a semiconductor, and to other electronic material elements, for example, an insulating film under a metal film. Can be done.

[0090] In addition to electronic materials, the use of the coating composition of the present invention can also form a siliceous film on the solid surface of various materials such as metals, ceramics, and wood.

. According to the present invention, a metal substrate (silicon, sus, tungsten, iron, copper, zinc, brass, aluminum, etc.) having a siliceous film formed on its surface, or a ceramic substrate having a siliceous film formed on its surface (In addition to metal oxides such as silica, alumina, magnesium oxide, titanium oxide, zinc oxide, and tantalum oxide, metal nitrides such as silicon nitride, boron nitride, and titanium nitride, and silicon carbide).

Claims

The scope of the claims

[1] A coating composition comprising a polyalkylsilazane compound, a siloxy group-containing polymer, and an organic solvent.

[2] The coating composition according to claim 1, wherein the siloxy group-containing polymer contains a polymer unit selected from the group consisting of acrylic acid, methacrylic acid, and a polyethylene oxide compound.

[3] The polyalkylsilazane compound comprises a repeating unit represented by the following general formula (1) and at least one unit represented by the general formula (2) or (3). 13. The coating composition according to any one of items 1-3.

[Chemical 1]

(In the above formula, R ¹ represents a hydrogen atom or an alkyl group having 13 to 13 carbon atoms, but it is not always possible for all R ¹ of the whole compound to be hydrogen at the same time.

R ² R ⁴ is a force independently representing a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ² — R ⁴ cannot be all hydrogen at the same time.

p, q, and r are each 0 or 1, 0≤p + q + r≤3,

R ⁵ — R ⁷ are each independently a hydrogen atom or a C 13 alkyl group. Not all R ⁵ and R ^{6 in the} entire compound can be hydrogen at the same time. R ^{8 to} R ¹¹ each independently represent a hydrogen atom or an alkyl group having 13 to 13 carbon atoms, but not all R ^{9 to} R ^{11 in the} whole compound are hydrogen at the same time. )

[4] The coating composition according to any one of [1] to [3], wherein the coating composition is formed by applying the composition on a substrate, or filling a mold or a groove, and further firing. A siliceous material.

[5] A semiconductor comprising the siliceous material according to claim 4 as an interlayer insulating film.

[6] The coating composition according to any one of claims 13 to 13 is pre-baked in a steam-containing atmosphere at a temperature of 50 to 300 ° C, and further calcined in a dry atmosphere at a temperature of 300 to 500 ° C. A method for producing a siliceous material.